1. Field of the Invention
The present invention is directed to a medical examination and/or treatment system of the type employing a catheter that is guided in the body of an examination or treatment subject.
2. Description of the Prior Art
Cardiac infarction is caused by diseases of the arterial coronary vessels (arterial sclerosis). Deposits (arterial sclerotic plaque) at the vessel wall lead to a reduction in the vessel diameter and ultimately can produce blockage of individual or a number of coronary vessels. It has been recognized that the risk of suffering a cardiac infarction is not primarily dependent on the reduction of the vessel diameter. On the contrary, it is also important whether the thin protective layer that covers the arterial sclerotic deposit is intact. When this breaks apart, then thrombocytes collect at the point of rupture, which completely close the vessel within a short time and thus causing the cardiac infarction.
A catheter has been conventional employed for examination or treatment of this condition, the catheter being advanced into the region of the endangered coronary vessel with simultaneous X-ray monitoring for identifying the position of the catheter and for monitoring the examination/treatment. The physician manually introduces such a catheter into the vessel system and displaces it therein. Even though the catheter is flexible, problems arise due to this manual guidance, particularly in the region of vessel bends and the like. The movement and positioning of the catheter, consequently, is problematical. A perforation of the vessel wall can occur if the tip of the catheter is too forcefully pressed thereagainst, as can easily occur due to the tight tolerances in the directional movement.
Another problem associated with procedures of this type is that the simultaneous X-ray monitoring supplies only information about the free volume, i.e. the unfilled volume, of the vessel but does not supply any information about the vessel wall and thus the problematical plaque deposits themselves. Although known examination and/or treatment systems supply important information for the physician, they do not supply all information required in the optimum case for an exact diagnosis.
German OS 40 37 586 discloses a medical probe for examining a body that emits electromagnetic waves that are acquired by a receiver arranged outside the body, from which the probe can be localized. An image of the probe can be displayed in an X-ray image, for example.
U.S. Pat. No. 6,298,261 discloses a catheter tracking system. A number of transducers are employed as locating aid, one of these being arranged on the head of the catheter.
These systems only serve for locating a catheter. The aforementioned problems in the manual movement of the catheter by a physician continue to exist. Moreover, the physician is not provided with any further information by these locating systems.
An object of the present invention is to provide an examination and/or treatment system that is improved compared to the above-discussed systems.
This object is achieved in accordance with the invention in an examination and/or treatment system having an X-ray image exposure system with a radiation source, a radiation receiver as well as a control and processing device that controls them. a catheter system having a catheter with at least one element that is provided in the catheter tip that generates a magnetic field and a device for generating an external magnetic field for guiding movement of the catheter within a patient, as well as an ultrasound image exposure system having a device integrated in the catheter tip for generating and for receiving ultrasound and having a control and processing device that controls this device.
The inventive system makes use of the known technique of monitoring the catheter movement as well as the vessel volume using an X-ray image exposure system. A simple or a bi-planar C-arm device, for example, can be utilized. The inventive system, further, employs a catheter system with a catheter that is not guided manually but is guided by means of a magnetic field generated externally of the patient. To this end, an element that generates a magnetic field at the catheter side is provided in the catheter tip. This magnetic field generated in the patient interacts with the external navigation or guidance magnetic field, which is modified for moving the catheter in terms of its position relative to the patient. In this way, directional control can be implemented quasi actively in the region of the catheter tip, which must necessarily be guided first around any vessel bends or the like, so that the catheter movement is significantly simpler and significantly more precise with respect to the positioning.
An ultrasound image exposure system also is utilized, the sound generation and reception device thereof being integrated in the catheter tip. Ultrasound images are directly registered from the inside of the vessel, showing the vessel wall in detail, so that the attending physician is provided with information about the appearance of the vessel wall.
Overall, the inventive system offers a number of advantages, namely a simple and extremely precise mobility and positionability of the catheter, as well as the availability of different images, namely the X-ray images showing the free vessel volume and the ultrasound images showing the detailed inside vessel wall and vessel structure. The physician thus is provided with image information that is important and should be combined for the diagnosis and that is essential for the correct treatment.
In an embodiment of the invention the X-ray images and the ultrasound images can be displayed at a common monitor, preferably simultaneously, so the physician can immediately combine the two images showing the same examination region with one another or compare them and process them in terms of image processing insofar as this is necessary.
For a simple operation of the treatment system with its various components, it is expedient to integrate the controller of the X-ray system and the controller of the ultrasound system and the controller of the device that generates the external magnetic field in a common control device, so that the operation of these sub-systems can ensue proceeding from a single control console.
It is especially expedient for the magnetic field of the catheter that is generated via the magnetic field-generating elements in the catheter tip to be variable given a catheter introduced into a patient, i.e. variable in field strength and/or field direction. In this way, the interaction of the magnetic field of the catheter side generated therewith with the external magnetic field can be varied. An electromagnet with a core and a coil is expediently employed as the element that generates the magnetic field, with the leads of the coil being guided in the catheter sheath so the coil can be energized in controlled fashion from outside the patient via a catheter control device. A field variation is possible in a simple way by a suitable control of the coil current. The field strength can be increased by increasing the current; the field direction changes due to a reversal of the direction of the current, etc. This control can ensue in a simple way if the catheter control device is fashioned as a separate, for example portable, device, so that it can be positioned close to the patient and long leadsxe2x80x94at least to the coilsxe2x80x94can be foregone. Of course, it is also conceivable to likewise integrate the catheter controller in the aforementioned common control device.
It is expedient to employ two or more electromagnets in order to obtain an additional degree of freedom of the field variation by superimposing the individual fields, given individually controllable electromagnets. It is also possible to drive at least some of the multiple electromagnets in common.
In a further embodiment of the invention the (at least one) electromagnet is arranged such that the magnetic field that can it generates resides essentially parallel to the longitudinal axis of the catheter. Alternatively, the (at least one) electromagnet can be arranged such that the magnetic field it generates resides essentially perpendicular to the longitudinal axis of the catheter. A different interaction with the external field (given an assumed, same field direction of the external field) derives dependent on what the field direction is, i.e. the force that is generated therewith and acts on the catheter tip is directed differently.
In a further embodiment at least two electromagnets arranged in this way are provided, with the magnetic field generated by one electromagnet residing essentially parallel and the magnetic field generated by the other electromagnet residing essentially perpendicular to the longitudinal axis of the catheter, so that both of the aforementioned guidance possibilities can be utilized. Additionally, at least one permanent magnet element can be provided in the region of the catheter tip, so that the operation of the electromagnet or electromagnets can be foregone, at least temporarily, if the magnetic field of this at least one permanent magnet element suffices for the movement.
In another embodiment of the invention the catheter controller communicates with the controller for generating the external magnetic field, and the control of the electromagnet or electromagnets ensues dependent on the control information of the magnetic field generating device. The catheter controller thus can react to changes in the momentary setting parameters of the magnetic field generating device or take these into consideration in the context of the control of the coil current, so that the supply of the coils with current always ensues according to the desired interaction.